U.S. National Library of Medicine

1. Visna-maedi virus

   A species of LENTIVIRUS, subgenus ovine-caprine lentiviruses (LENTIVIRUSES, OVINE-CAPRINE), that can cause chronic pneumonia (maedi), mastitis, arthritis, and encephalomyelitis (visna) in sheep. Maedi is a progressive pneumonia of sheep which is similar to but not the same as jaagsiekte (PULMONARY ADENOMATOSIS, OVINE). Visna is a demyelinating leukoencephalomyelitis of sheep which is similar to but not the same as SCRAPIE.